I guess you could schedule a network scan at the end of the day when you know all systems must be turned off and then run another scan the next morning when they are turned on.

This would be done by Spiceworks using ping so anyone smart enough to block ICMP might be able to get around that. If that is not a concern then you might want to look at doing a ping sweep instead of using Spiceworks to see if the computers are offline. That way you don't fill your Spiceworks inventory with offline systems and unecessary alerts. You could also look into doing an ARP scan since that might help with people blocking ICMP traffic.

For a ping sweep you can look into nmap. I haven't used a tool for ARP scans in a while so I can't recall any names from the top of my head but I'll post if I remember any.

Forgot to mention that you may also be able to get this information from the EventViewer of the computers.

You could even enable Shutdown Tracker which might help you track the shutdown reasons. You could set it to default to something like "nightly shutdown" or something like that.

I haven't played with the event log features of Spiceworks so I'm not sure what it can do but if you can get reports from Spiceworks using the computer events as source you could potentially generate reports of systems that are not being shutdown.

My company’s policy is to turn all computers off (to shutdown) at the end of the working day.

I want to make a report that will show me what user did NOT turn off his computer, computer ip...

I do not want to turn off automatically computers I just want to know who is not fooling company’s policy.

Okay, that helps. SpiceWorks could make a report to tell you what machines are still up. That would be a custom report that you would need to make more likely or find as a downloadable report. Then you will need to write your won scripts to shut them down, SW will not control computers for you.